Age and sex-based distribution of lumbar multifidus muscle atrophy and coexistence of disc hernia: an MRI study of 2028 patients.

PURPOSE: We aimed to investigate the prevalence of lumbar multifidus muscle (LMM) atrophy in patients having mechanical low back pain with and without disc hernia.

METHODS: In total, 2028 lumbar magnetic resonance imaging scans of low back pain patients (age range, 18-88 years) were re-evaluated retrospectively. LMM atrophy was visually assessed in axial sections of L4-L5 and L5-S1 levels.

RESULTS: LMM atrophy prevalence at both levels was significantly higher in subjects ≥40 years compared with younger adults (P < 0.001). LMM atrophy was significantly more frequent in women than in men (P < 0.001). Among patients with low back pain without hernia, LMM atrophy was significantly more frequent than normal muscle (n=559 vs. n=392; P < 0.001). Frequency of LMM atrophy in low back pain patients without disc hernia was 13%. Hernia was more frequent in patients with LMM atrophy compared with patients without atrophy (P < 0.001).

CONCLUSION: LMM atrophy is more common in women; its prevalence and severity are observed to increase with advancing age, and disc hernia is found more frequently in individuals with LMM atrophy.